The major automobile manufacturers have used a lead based body solder to fill depressions in car bodies such as between the roof and rear fenders before the car bodies are painted. These solders generally are alloys of lead with tin or antimony. These solders have a temperature melting range that permits the solder to be melted and applied to the body with a spatula before the solder solidifies. On cooling the solder solidifies and can be sanded smooth to a feathered edge before painting.
The metal in this solder, viz lead, tin and antimony, are of high atomic weight and generally considered to be highly toxic. Consequently the automobile companies and others have attempted to develop body solders of an organic base that were free of these metals.